Interaction with Job Control

If the debugger is attached to a process that is stopped by job control
(that is, it stopped in response to SIGTSTP, SIGTTIN, or SIGTTOU), the process
may not be able to be set running again when it is continued by a continue
dcmd. If the victim process is a member of the same session (that is, it
shares the same controlling terminal as MDB), MDB will attempt to bring the
associated process group to the foreground and continue the process with SIGCONT
to resume it from job control stop. When MDB is detached from such a process,
it will restore the process group to the background before exiting. If the
victim process is not a member of the same session, MDB cannot safely bring
the process group to the foreground, so it will continue the process with
respect to the debugger but the process will remain stopped by job control.
MDB will print a warning in this case, and the user must issue a fg command from the appropriate shell in order to resume the process.